Diastereo- and enantioselective preparation of oxazolines via the base-catalysed aldol reaction of isocyanoacetates with aldehydes using cinchona alkaloids
作者:Rui-Chuan Diao、Wen-Tao Zhao、Shen Li
DOI:10.3184/174751916x14683198156665
日期:2016.9
A diastereo- and enantioselective base-catalysed aldol reaction of t-butyl isocyanoacetate with aldehydes under phase-transfer catalytic conditions yielded 19 4,5-disubstituted oxazolines, 16 of which are novel. Key to success was the use of a free 9-OH-containing cinchona alkaloid-based quaternary ammonium salt bearing bulky and electron-withdrawing aryl groups on the N-benzyl moiety. This process
在相转移催化条件下,异氰乙酸叔丁酯与醛的非对映选择性和对映选择性碱催化羟醛反应产生了 19 种 4,5-二取代的恶唑啉,其中 16 种是新的。成功的关键是使用含游离 9-OH 的金鸡纳生物碱季铵盐,在 N-苄基部分上带有庞大的吸电子芳基。该过程同时耐受芳香族和脂肪族醛,提供相应的手性恶唑啉产物,其非对映选择性高达 20:1,对映选择性高达 78% ee。